What grosses people more, the fact of breastfeeding going past the age of diapers or the fact the kid that can stand has his mouth at a woman’s nipple?

There is a lot of reaction to this Time cover, most of what I heard was not good. I wonder is it the fact people have this expectation that a breastfeeding child be in diapers or the expectation that any kid wearing toddler clothes and able to walk, talk and stand should not have their mouth at a woman’s nipple, even worse if it is a boy over a girl?